AGRtC.  DEP 


BIOLOGY 

LIBRARY 

G 


CONTRIBUTIONS 


TO  THE 


BY 

J.  J.  RIVERS, 

Curator  of  the  Museum,  University  of  California. 


STATE  OFFICE 


SACRAMENTO: 

JAMES  J.  AYERS,  SUPT.  STATE  PRINTING. 

1886. 


CONTRIBUTIONS 


LARViL  HE! 


BY 

J.  J.  RIVERS, 

Curator  of  the  Museum,  University  of  California. 


SACRAMENTO: 

STATE   OFFICE JAMES   J.    AYERS,    SUPT.    STATE    PRINTING. 

1886. 


Mainlib7 

AGftlC.  D€PT, 


CONTRIBUTIONS 

TO   THE 

LARVAL  HISTORY  OF  PACIFIC  COAST  COLEOPTERA. 


By  J.  J.  RIVERS,  Curator  of  the  Museum,  University  of  California. 


The  study  of  systematic  entomology  affords  the  student  but  a  dim  idea 
of  what  insects  are  noxious  and  what  are  innoxious.  The  distinctive  char- 
acters upon  which  the  systematic  entomologist  builds  classification  need 
not  be  and  generally  are  not  the  characters  of  prime  importance  to  the 
economic  entomologist.  The  names  of  many  of  the  groups  of  Coleoptera 
afford  a  slight  generalized  description  which  is  often  misleading.  In  the 
present  state  of  entomologic  science,  where  systematic  method  is  given 
precedence  over  the  biologic,  it  is  dangerous  to  attempt  to  make  a  general 
statement  of  the  habits  of  a  single  genus,  and  impossible  to  generalize  the 
habits  of  a  group  or  family. 

The  most  valuable  contribution  to  the  life  history  of  American  insects 
which  is  generally  accessible  is  Dr.  Packard's  "  Insects  Injurious  to  Forest 
and  Shade  Trees."  *  In  his  introduction ,  the  author  states  that  this  work 
is  purely  tentative,  and  designed^)  elicit  the  results  of  the  observations  of 
students  of  economic  entomology.  It  is  on  that  account  that  I  feel  at  lib- 
erty to  comment  upon  or  question  certain  of  Dr.  Packard's  statements. 

On  page  118,  op.  cit:  Prionus  laticollis,  Drury,  is  noted  as  injurious  to 
the  poplar.  If  Prionus  destroys  living  trees  in  other  parts  of  America,  it 
has  no  such  destructive  habit  in  California;  in  fact,  the  charge  against 
borers  that  they  destroy  trees  is  a  very  old  one,  but  by  no  means  substan- 
tiated by  my  own  observations.  P.  Californicus  goes  through  its  trans- 
formations in  the  roots  of  oaks,  but  these  roots  were  dead  in  every  case 
observed  by  me,  and  usually  belonged  to  stumps  whose  trunks  had  been 
felled  years  before.  Last  year  I  bred  several  from  the  decayed  part  of  an 
old  oaken  chopping  block.  In  fact,  Dr.  Packard  himself  throws  some 
doubt  upon  the  destructive  habit  of  P.  latiocollis,  for  in  his  note  he  quotes 
the  report  for  1872  of  Prof.  S.  J.  Smith,  Entomologist  to  the  Connecticut 
Board  of  Agriculture,  as  follows:  "  I  have  noticed  it  in  logs  of  poplar,  bass- 
wood,  and  oak,  and  in  the  trunks  of  old,  decaying  apple  trees." 

On  page  137,  op.  cit.,  is  the  following:  "We  have  found  Buprestid  and 
Longicorn  borers  in  a  dead  sweet  gum  tree."  The  caption  at  the  head  of 
the  page,  "  Insects  Injurious  to  the  Sweet  Gum,"  seems  designed  to  lead  to 
the  inference  that  these  borers  killed  the  tree.  But  my  observation  is  that 
the  larvae  of  insects  of  the  two  families  noted  feed  only  on  dead  wood. 

Again,  on  the  same  page  (137),  Ptilinus  basalis  and  Micracis  hirtella 
are  listed  as  injurious  to  the  California  bay.  These  species  are  both  found 
in  Berkeley,  and  I  have  observed  their  habits  for  the  last  seven  years,  and 
as  a  result  of  such  observation  I  am  in  a  position  to  assert  that  they  bore 
into  the  twigs  of  the  tree  mentioned  only  when  dead,  dried,  and  decaying. 

On  page  71,  op.  cit.,  we  find  a  figure  of  Oncideres  cingulatus  in  the  act 
of  girdling  a  hickory  twig.  In  connection  with  this  insect  we  meet  with 

*U.S.  Entomological  Commission,  JMfetm  V^Sington,  1881. 


one  of  the  most  interesting  and  remarkable  points  in  the  whole  range  of 
insect  biology.  For,  knowing  that  its .  larva  will  have  to  feed  upon  dead 
and  sapless  wood,  this  beetle,  at  the  time  of  depositing  its  egg  in  the  living 
and  easily  penetrated  green  wood,  has  instinct  or  forethought  to  girdle  the 
twig,  and  thus  assure  the  future  larva  the  conditions  necessary  for  its 
metamorphosis. 

The  question,  "Are  Curculio  larva  lignivorous  ?"  has  been  partially  dis- 
cussed in  Bulletin  of  the  Brooklyn  Entomological  Society,  vol.  vii,  p.  150, 
by  Warren  Knaus,  and  in  Entomologica  Americana,  vol.  i,  p.  18,  by  W.  H. 
Harrington.  The  question  was  brought  up  by  the  finding  of  Wollostonia 
quercicola  in  cottonwood  logs  in  an  advanced  stage  of  decay.  The  Curcu- 
lios  are  a  group  of  insects  in  systematic  value  the  equivalent  to  a  sub-order, 
and  known  as  the  Rynchophora  (Latreille),  which  bear  certain  intimate 
resemblance  to  one  another  in  the  perfect  and  final  forms,  while  in  their 
larval  stage  they  may,  and  certainly  do,  differ  in  many  particulars  of  habit. 
W.  quercicola  belongs  to  the  Calandridae,  a  family  abounding  in  species 
whose  habit  in  the  larval  stage  is  preeminently  to  feed  on  dry  wood.  The 
metamorphoses  of  the  Rhynchophora  (Latr.)  are  not  at  all  well  known, 
but  I  have  bred  the  following,  belonging  to  this  sub-order,  and  have  found 
them  to  be  lignivorous  in  the  larval  stage: 

PLATYRHINUS  LATIROSTRIS  Fabr. — Decaying  oak  stumps  highly  charged 
with  mycelia  of  a  fungus. 

SCOLYTUS  DESTRUCTOR  Oliv. — Dead  sapwood  of  elm. 
MESITIS  TARDII  Woll. — Decaying  beech. 
MONARTHRUM  HuTTONi  Woll. — Various  hard  woods. 
HYLESINUS  CRENATUS  Fabr. — Dying  ash. 
ANTHRIBUS  ALBINUS  Lin. — Old  wood. 
BRACHYTARSUS  SCABROSUS  Fabr. — Elm  bark. 
RYNCOLUS — several  species. — Bark  of  trees. 

The  foregoing  are  old  world  species  of  Curculios  that  do  not  affect  a 
herbaceous  diet;  and  the  three  following  species  are  of  similar  habits. 

SCOLYTIDJE. 

MONARTHRUM  SCUTELLARE  Lee. — Bark  of  dead  Quercus  agrifolia. 
MONARTHRUM  DENTIGERUM  Lee. — Bark  of  dead  Quercus  agrifolia. 

MICRACIS  HIRTELLA  Lee. — Dead  branches  of  California  laurel,  Umbellu- 
laria  Californica. 

The  Brenthidae  are  well  known  to  have  the  general  habit  of  perforating 
trees  and  of  depositing  a  single  egg  in  each  hole  thus  made,  by  this  means 
providing  that  the  larva  shall  have  a  full  supply  of  the  wood  upon  which 
it  feeds. 

The  question,  then,  should  not  be:  are  Curculio  larva?  lignivorous?  but 
rather,  how  many  have  that  habit?  .  In  a  great  group  like  this  of  Curculios, 
comprising  many  forms  varying  greatly  from  one  another,  one  can  easily 
appreciate  the  fact  that  we  meet  with  many  different  tastes  and  habits. 


Some  are  known  to  feed  upon  all  kinds  of  grain  in  store;  one  finds  its  food 
in  rice,  another  in  barley,  and  others  in  maize.  Many  species  of  Balanius 
undergo  their  changes  in  nuts,  the  larva  feeding  upon  the  kernels;  another 
group  is  to  be  found  in  Cynips  galls;  and  one  species,  geographically  dis- 
tributed from  San  Diego  to  Alaska,  is  to  be  found  beneath  seaweed  upon 
the  shores.  Enough  has  been  instanced  to  show  clearly  that  we  can  draw 
no  inference  from  the  fact  that  two  insects  are  found  in  the  same  natural 
group,  that  for  that  reason  their  habits  are  similar;  and  it  is  evident  that  a 
classification  by  habits  would  be  of  little  aid  to  the  systematic  entomologist. 

CHRYSOMELID^E. 

DIABROTICA  soRO^Lec. — This  is  a  most  destructive  insect  to  our  peach 
orchards,  and  is. not  as  yet  sufficiently  studied.  If  it  resembles  in  habit 
the  eastern  species  of  the  genus,  and  feeds  in  the  larva  stage  upon  the  roots 
of  cereals,  it  may  be  possible  to  rid  ourselves  in  some  degree  of  this  pest 
by  some  rotation  of  crops.  In  the  meanwhile  sprays  and  washes  are  beyond 
a  doubt  not  only  useless,  but  in  most  cases  a  positive  injury.  We  shall 
have  to  study  further  before  speaking  positively  of  the  larval  history  of  this 
insect  pest. 

PTINID^E. 

PTINUS  INTERRUPTUS  Lee. — Black  fungus  of  the  laurel,  Umbellularia 
Californica. 

PTINUS  QUADRIMACULATUS  Melsh. — Decayed  Ceanothus  thyrsiflorus. 
HEDOBIA  GRANOSA  Lee. — Dead  branches  of  Umbellularia  Californica. 

HADOBREGMUS  GIBBICOLLIS  Lee. — Decaying  wood  of  Myrica  Californica 
and  dead  willow. 

VRILLETTA  CONVEX  A  Lee. — Dead  Quercus  agrifolia. 

PTILINUS  BASALTS  Lee. — Dead  twigs  of  Umbellularia  Californica. 

SINOXYLON  DECLIVE  Lee. — Any  dead  tree  or  unpainted  wood,  very  partial 
to  wine  casks  and  oak  barrels.  The  depredations  are  done  by  the  beetle 
while  boring  for  a  suitable  place  to  deposit  its  eggs.  Its  burrow  is  straight 
across  the  grain  of  the  wood,  reaching  the  interior  of  the  cask,  causing 
waste  and  deterioration  of  the  contents.  Hot  solution  of  alum  applied  to 
the  outside  of  the  casks  will  prevent  boring. 

POLYCAON  STOUTII  Lee. — Dead  and  dried  willow. 

POLYCAON  CONFERTUS  Lee. — Found  boring  into  a  slab  of  chestnut  oak 
that  had  been  deposited  for  years  in  the  museum  of  the  University  of  Cali- 
fornia; also  bred  from  the  stem  of  dead  apricot  trees  that  had  been  grafted 
on  a  peach  root. 

There  appears  strong  evidence  that  these  trees  were  not  destroyed  by  the 
borer,  but  through  the  influence  of  the  "black  knot"  on  the  roots,  they 
being  diseased  with  knobs  as  large  as  a  man's  fist  on  every  root;  while  all 
the  trees  killed  had  the  root  diseased,  only  a  portion  was  infested  with  the 
larva  of  this  beetle. 

During  July,  while  on  a  visit  to  the  Napa  Valley,  I  saw  a  lot  of  roots 
and  stems  of  grapevines  that  had  been  grubbed  the  year  before.  These 
were  old  vines,  and  had  been  discarded  on  account  of  splitting  of  the  main 
stem.  On  examination  these  were  found  to  contain  both  the  worm  and 


6 

the  beetle  forms  of  Polycaon  confertus,  showing  that  the  metamorphosis 
takes  place  in  dead  wood. 

Many  similar  observations  made  by  myself  and  others  go  to  show  that 
in  the  larval  stage  this  insect  is  xylophagous.  On  the  other  hand,  there  is 
indisputable  proof  that  the  beetle  infests  living  trees  by  entering  the  twigs 
at  the  axils  of  the  leaves. 

LYCTUS  STRIATUS  Melsh. — Devastates  furniture  made  of  California  laurel, 
Umbellularia  Californica,  Dr.  Packard,  op.  cit.  p.  75,  quotes  Dr.  LeConte 
as  saying  that  it  affects  the  trunks  and  branches  of  Carya  tomentosa.  This 
is  not  borne  out  by  my  observations,  as  I  am  well  satisfied  that  the  larva 
lives  in  dead  and  dry  wood. 

SCARAB^EID^E. 

POLYPHYLLA  DECEMLiNEATA  Say. — Larva  that  produced  this  species  was 
found  in  the  earth  from  one  to  two  feet  from  the  surface,  among  root  fibers 
of  a  coarse  grass  and  roots  of  a  California  laurel,  Umbellularia  Californica. 
The  earth  was  sandy  loam  situated  upon  the  banks  of  a  river,  and  which 
is  overflowed  during  the  rainy  season  of  the  year. 

ODONTAEUS  OBESUS  Lee. — This  has  a  light  chestnut  larva  with  tufts  of 
bristles  surrounding  each  spiracle.  Mandibular  and  clypeal  portions  well 
developed,  redder  in  color,  and  thicker  in  texture  than  any  other  part. 
The  legs  are  prominent.  Feed  upon  rootlets  of  Umbellularia  Californica. 
It  is  much  infested  with  a  small,  pale-colored  mite,  which  is  evidently  par- 
asitic on  the  species. 

LUCANID^E. 

PLATYCERUS  OREGONENSIS  (Westwood). — Dead  trees  of  Photinia  arbuti- 
folia,  Umbellularia  Californica,  Quercus  agrifolia,  and  Eucalyptus. 

PLATYCERUS  AGASSII  Lee. — Decayed  trees  of  Arbutus  Menziesii;  also  in 
wood  too  much  decayed  to  be  identified. 

SINODENDRON  RUGOSUM  Mann. — Decayed  oak,  Quercus  agrifolia. 

The  five  hundred  and  twenty-two  North  American  species  of  Ceramby- 
cidse  are  all  borers;  the  insect  deposits  its  egg  in  a  hole  perforated  in  the 
wood,  and  the  larva  penetrates  further  and  further  according  to  a  rhyth- 
mic order  peculiar  to  the  species  until  its  metamorphoses  are  completed. 
The  following  is  a  list  of  the  Californian  species  whose  habits  I  have 
observed: 

CERAMBYCimE. 

ERGATES  SPICULATUS  Lee. — Rotting  coniferous  trees.  Bred  from  Sequoia 
sempervirens,  Pinus  insignis,  Abies  Douglasii,  etc. 

PRIONUS  CALIFORNICUS  Mots. — Bred  from  rotten  damp  roots  of  Quercus 
agrifolia. 

ASEMUM  NITIDUM  Lee. — Decayed  Pinus  insignis. 

HYLOTRUPES  LIGNEUS  Fab. — Dead  trees  of  Libocedrus  decurrens. 

ELAPHIDION  IMBELLE  Lee. — Bred  from  decayed  oak  near  San  Diego,  Cal., 
by  F.  E.  Blaisdell. 

HOLOPLEURA  HELENA  Lee. — Dead  twigs  of  Umbellularia  Californica. 


ROSALIA  FUNEBRIS  Mots. — Decaying  Umbellularia  Californica  among 
the  mycelia  of  some  fungus. 

XYLOTRICHUS  NAUTICUS  Mann. — Dead  sapwood  of  the  oak,  Quercus  agri- 
folia. 

XYLOTRECHUS  OBLITKRATUS  Lee.,  insignis  F. — Dead  branches  of  willow. 

NECYDALIS  L^EVICOLLIS  Lee. — Decayed  oak,  Quercus  agrifolia,  and  in 
dead  Eucalyptus  globulus. 

LEPTURA  L^ETA  Lee. — Dead  Quercus  agrifolia  and  Quercus  sp. 
LEPTURA  GRASSIPES  Lee. — Decayed  wood  of  Umbellularia  Californica. 

SYNAPHCETA  GUEXI  Lee. — Dead  limbs  of  California  buckeye,  JEsculus 
Californica. 

POGONOCHERUS  CRiNiTUS  Lee. — Dead  branches  of  Quercus  agrifolia. 

TROGOSITID.E. 

TROGOSITA  VIRESCENS  Fab. — Dead  Libocedrus  and  several  kinds  of  oak. 

CLERID^E. 

THANASIMUS  EXTMIUS  Mann. — Dead  twigs  of  Umbellularia  Californica. 

MELANDRYID^E. 


RIVERSII  Lec. — Larva  feeds  in  decaying  trees  of  Madroria, 
Arbutus  Menziesii.  In  trees  in  position  the  insect  is  found  in  the  primary 
forks  of  the  roots,  and  in  prostrate  logs  among  the  more  seasoned  fibers  of 
the  wood. 

LAMPYRID^E. 

Among  many  entomological  enigmas  of  long  standing  is  one  that  is  about 
being  solved.  From  time  to  time  in  many  parts  of  the  United  States,  large 
luminous  larvae  of  some  Coleopteron  have  been  found,  and  it  has  been  con- 
jectured that  these  larvae  belong  to  some  of  the  Elateridae,  the  general 
supposition  being  that  they  were  larvae  of  the  genus  Melanactes.  Every 
attempt  at  breeding  them  resulted  in  failure  because  their  natural  food 
was  unknown.  I  have  recently  found  what  their  food  consists  of.  Before 
making  this  discovery  I  had  arrived,  from  a  careful  study  of  the  anatomy 
of  the  mouth  parts  of  these  larvae,  at  the  conclusion  now  confirmed,  that 
they  are  carnivorous  in  habit. 

Their  food  consists  of  the  vegetable  feeding  Myriapoda,  particularly  of 
Julus  and  Polydesmus,  with  a  preference  for  Julus,  because  the  large  area 
of  the  rings  of  this  genus  affords  space  for  the  larva  to  penetrate  the  interior 
of  the  Myriapod.  Its  manner  of  feeding  is  to  seize  the  hinder  part  of  the 
Julus,  and  perforate  a  segment,  reaching  the  soft  inner  parts,  which  it 
devours  at  leisure,  creeping  through  many  segments  without  disjointing 
them,  and  remaining  inside  these  rings  for  days  at  a  time,  till  one  can 
see  little  else  but  the  slowly  wriggling  form  of  the  dying  Julus. 

I  have  a  full  fed  larva,  which  I  hope  will  go  through  its  metamorphosis, 
and  solve  the  problem.  And  now  its  mode  of  life  is  made  known,  other 
persons  who  are  equally  anxious  with  myself  that  nature  shall  yield  this 


8 

long  kept  secret,  can  apply  themselves  with  renewed  energy  to  the  task  of 
discovering  the  identity  of  the  perfect  insect. 

This  luminous  larva  has  proved  to  be  the  form  of  the  female  in  a  Lam- 
pyrid  beetle,  better  known  as  Zarhipis  Riversi  Horn.  Or  if  not  a  perfectly 
metamorphosed  female,  possesses  the  powers  of  that  sex  to  produce  ova 
and  attract  the  male.  The  grub  or  larva  had  fed  all  winter,  and  in  March 
sloughed  its  skin  and  remained  motionless,  coiled  in  a  cell  of  earth,  for 
three  weeks,  and  kept  a  uniform  pale-cream  color  without  luminosity,  but 
gradually  the  center  of  the  dorsal  plates  became  darker,  and  in  the  ratio 
of  coloring  so  was  the  reappearance  of  the  phosphorescent  light;  when  fully 
restored  in  strength  it  became  very  active  and  strongly  luminous,  but  it  did 
not  eat.  In  about  a  week  ft  disappeared  beneath  the  earth,  and  remained 
out  of  sight  for  nearly  a  month,  and  thinking  it  had  changed  into  the  pupa 
state  I  disturbed  it,  and  found  no  change  to  have  taken  place.  I  returned 
it  to  the  jar,  placing  the  coiled  insect  upon  the  top  of  the  earth,  where  it  lay 
motionless  for  two  days.  On  the  morning  of  the  third  day  I  found  it  had 
sloughed  another  skin,  but  this  time  a  very. thin  covering  of  uniform  pale 
brown,  and  the  insect  itself  had  disappeared  into  the  earth.  This  last  dor- 
mant stage  seems  to  represent  its  pupa  state.  I  unearthed  it  again  and 
found  it  very  soon  afterwards  to  assume  great  activity  and  bright  lumin- 
osity, but  it  would  take  none  of  the  usual  food.  Taking  the  jar  which  con- 
tained this  insect  into  the  open  air  for  the  purpose  of  supplying  it  with  fresh 
earth,  and  while  doing  so,  several  male  specimens  came  flying  around  the 
jar,  and  one  example  dropped  swiftly  upon  what  had  been  supposed  to  be 
the  larval  form.  The  male  soon  attempted  copulation.  The  attraction  of 
the  female  was  perfect,  and  by  it  I  captured  eleven  males.  The  eleven 
males  attracted  were  not  all  of  the  form  known  as  Z.  River  si  Horn,  some 
represent  the  Z.  piciventris  Lee.,  and  these  facts  will  cause  a  revision  of  the 
genus,  and  the  four  species  will  be  reduced  one  under  the  name  of  Zarhipis 
integripennis  Lee. 

Description  of  a  form  of  the  female: 

Apterous,  vermiform,  segmented,  retractile,  phosphorescent.  Number 
of  joints,  exclusive  of  the  head,  twelve.  Legs,  six;  two  on  each  of  the 
three  anterior  segments,  or  on  those  portions  underneath  representing  the 
pro,  meso,  and  metasternum.  Length,  when  extended  in  walking,  two 
and  a  quarter  inches;  and  the  width,  across  the  widest  part,  five  sixteenths 
of  an  inch. 

Head,  corneous,  shining  black,  and  not  well  defined,  and  when  at  rest, 
hidden  beneath  the  anterior  segment.  The  prominent  character  of  the 
head  consists  of  a  pair  of  curved,  hook-like  mandibles,  like  those  of  the 
male.  Antennae,  short,  straight,  four-jointed;  the  apical  joint  bristle-like, 
and  growing  from  the  side,  at  the  end  of  the  previous  joint,  which  is  the 
largest,  and  tubular  in  form. 

Maxillary  palpi,  five-jointed,  four  being  nearly  equal  and  bead-like. 

Labial  palpi  appear  two-jointed.  The  antennae  and  palpi  being  short, 
stand  stiffly  out  from  their  base. 

Dorsal  surface  consists  of  twelve  thin  corneous  plates,  the  three  anterior 
being  narrowed  in  front,  and  all  having  an  impressed  line  through  the 
longitudinal  center.  The  plates  are  shining,  blackish  brown,  marginal 
transversely  with  transparent  olive  green,  and  upon  the  side  margins  with 
opaque  pale-yellow,  interspersed  with  olive,  which  colors  intermixed  obtain 
upon  the  sides  arid  under  parts  generally. 

Spiracles  upon  the  sides  of  the  fourth  to  the  eleventh  segments,  inclusive, 
and  just  below  the  spiracles  on  the  same  segments  is  a  double  fold,  form- 


ing  a  broken  lateral  ridge.  The  other  segments  bear  but  a  single  fold  and 
no  spiracles. 

The  thoracic  region  bearing  the  legs  exhibits  indistinct  sutures  and  folds 
presenting  but  a  faint  resemblance  to  analogous  parts  in  other  Coleoptera, 
and  yet  is  strongly  of  the  Lampyrid  type. 

Legs  of  the  Lampyrid  type,  four-jointed,  and,  like  females  of  the  group, 
have  a  short  obtuse  tarsal  claw. 

This  is  a  handsome  insect  when  living,  and  is  the  most  brilliant  "glow- 
worm "  known.  The  light  appears  most  intense  on  the  cross  margins  of 
the  dorsal  plates,  but  the  luminosity  is  also  strong  on  all  the  margins,  as 
well  as  along  the  lateral  edges.  Sometimes  the  insect  appears  checkered 
by  being  banded  with  phosphorescence. 

.There  are  some  more  facts  to  learn  about  this  peculiar  insect.  Why  the 
larva  should  be  luminous,  and  yet  have  nothing  to  attract;  and  why  the 
adult  female  should  be  luminous,  while  the  male  is  not  nocturnal,  but 
roams  in  the  sunlight.  The  habit  of  the  'male  is  to  appear  on  the  wing,  in 
temperate  heat,  from  9  A.  M.  to  4  p.  M.,  but  during  the  hottest  weather  it 
does  not  appear  until  the  sun  is  declining. 

Perhaps  there  is  yet  to  be  discovered  another  form  of  the  female,  without 
luminosity,  and  perhaps  more  perfect  in  its  parts,  and  non-luminous. 

Some  more  questions  are:  What  are  the  differences  in  the  larval  form 
of  the  sexes,  or,  are  there  any  larval  differences  of  the  sexes?  The  answers 
to  these  queries  will  only  come  after  observations;  but  the  answer  to  the 
one  concerning  the  luminous  character  may  give  way  to  theory,  and  it  may 
be  suggested  that  the  luminous  quality  is  inherited,  and  though  without 
use  in  this  species  because  of  the  diurnal  habit,  yet  may  be  a  derived  char- 
acter that  is  only  of  use  when  the  habit  of  the  insect  is  nocturnal.  But  it 
must  be  considered  that  the  plumose  antennae  of  the  male  would  indicate 
that  it  seeks  its  mate  by  scent. 

This  species  is  in  no  sense  an  injurious  insect,  but,  on  the  contrary,  may 
be  considered  as  beneficial  to  agriculture,  having  an  entirely  carnivorous 
habit. 


A  NEW  SPECIES  OF  CALIFORNIAN  COLEOPTERA. 


By  J.  J.  RIVERS,  Curator  of  Museum,  University  of  California. 


BBADYCINETUS,    HORN. 

Bradycinetus  Hornii,  n.  sp. 

Male:  Form,  robust,  elliptical.  Color,  ferruginous 
brown,  shining;  head,  tips  of  armature,  margins  of  pro- 
thorax,  and  a  spot  near  the  outer  margin  of  prothorax, 
either  dusky  or  black.  Head:  Clypeus  transverse  and 
feebly  angulate  at  the  sides,  the  front  edge 
rising  increasingly  backward,  until  just  be- 
fore reaching  the  clypeal  suture  it  ends  in 
a  well  formed  tubercle  on  either  side;  be- 
Male.  hind  the  sutural  line  on  the  vertex  is  a 

very  prominent,  stout,  conical  horn;  three  fourths  of  the  lower  portion  of 
the  horn  and  the  whole  of  the   frontal  area  finely  rugose.      Antennae: 
funicle  shining,  chestnut;  club  paler,  not  shining.     Thorax:  subtriangular, 
2 


10 

deepest  longitudinally  through  the  center;  noticeably  wider  than  the  elytra 
at  their  juncture,  and  rather  wider  than  their  greatest  breadth;  seen  from 
above  the  front  margin  appears  truncate  in  the  middle,  then  trends 
obliquely  forward  to  the  angles  which  are  prominent;  sides  straight  for  a 
short  distance,  posterior  angles  strongly  rounded;  posterior  margin  much 
extended  in  the  middle  with  distinct  sinuations  toward  the  angles.  The 
front  area  deeply  concave,  surmounted  with  four  well  formed  tubercles; 
two  occupying  the  center,  bold  and  projecting  over  the  concavity,  two 
others,  one  on  either  side  of  the  central  two  situated  near  the  anterior 
margin  of  the  thorax  at  its  exterior  angles.  The  area  around  the  two 
anterior  tubercles  very  rugosely  punctate ;  and  transversely  across  the  disc 
are  large  distinct  punctures  nowhere  extending  to  the  posterior  margin.  A 
well  defined  margin,  re  flexed  at  the  sides,  surrounds  the  whole.  Elytra: 
very  convex,  obtusely  rounded  behind,  having  fourteen  well  defined  and 
regularly  punctured  striae,  the  interstices  of  which  are  flattened  and  indis- 
tinctly wrinkled.  The  under  side  paler  than  the  upper;  dense  fringes  of 
light  chestnut  hair  line  the  reflexed  portion  of  the  thorax  and  elytra,  while 
the  femora,  tibia,  and  tarsal  joints,  as  well  as  the  lower  side  generally,  are 
well  supplied  with  rather  long  chestnut  hair.  Length  .48-. 52  inch. 

Female:  Form  and  color  as  in  male.  Labrum  pro- 
jecting, rugose,  covering  the  mandibles.  Head :  clypeal 
margin  raised;  a  feeble  tubercle  just  in  front  of  the 
clypeal  suture,  immediately  behind  which  is  a  central 
transverse  ridge,  undivided,  slightly  higher  in  the 
middle  and  slightly  apiculate  at  either  end.  Anten- 
nae less  robust  than  in  the  male.  Thorax :  very  convex, 
shining;  outline  obtusely  triangular;  anterior  margin 
Female.  seen  from  above,  truncate  in  the  center;  angles  pro- 

duced; sides  rounded;  posterior  margin  much  produced  to  meet  the  scu- 
tellum,  sinuate  toward  the  angles  which  are  rounded;  the  front  discal  area 
characterized  by  a  bi-lobed  transverse  raised  line,  at  either  end  of  which, 
outward  and  forward,  is  a  well  formed  but ^ depressed  tubercle;  behind 
which  line  the  disc  is  dense  with  coarse  corrugated  punctures,  which 
become  scattered  and  plain,  nowhere  reaching  the  posterior  margin,  but 
taking  a  transverse  course,  barely  reach  the  side  margins,  where  they 
become  less  distinct.  -  Elytra:  much  the  same  as  in  the  male,  but  the 
interstices  of  the  fourteen  punctate  striae  a  trifle  more  wrinkled  and  much 
more  convex.  Length,  smaller  than  the  male. 

Habitat:  burrowing  in  the  ground  near  the  City  of  Sonora,  Tuolumne 
County,  California;  found  also  in  Sacramento  County. 

The  name  selected  for  this  species  is  intended  to  be  a  small  tribute  of 
honor  to  Dr.  George  H.  Horn,  the  eminent  Coleopterist,  as  a  slight  return 
for  many  favors. 

STRIDULATING    ORGANS. 

The  sound  of  stridulating  was  first  heard  by  Mr.  Charles 
Fuchs,  of  Alameda,  who,  having  living  specimens,  made  exam- 
inations for  the  source  of  the  sounds,  and  was  rewarded  by  find- 
ing the  stridulating  apparatus  to  be  three  bands  situated  one 
each  upon  the  fourth,  fifth,  and  sixth  dorsal  segments,  are  well 
developed,  and  when  magnified  show  that  these  bands  are  set  with  bristles 
in  diagonal  rows,  the  points  of  the  bristles  are  bent  downward,  which,  by 
the  quick  contraction  of  the  abdomen,  these  hooked  bristles  are  brought 
in  repeated  contact  with  the  edge  of  the  elytra  arid  thus  causing  the  vibra- 
tions known  as  stridulating. 


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